<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>Document</title>
  </head>
  <body>
    <h2 class="counter">0</h2>
    <button class="increment">+1</button>
    <button class="decrement">-1</button>

    <script>
      const counterEl = document.querySelector('.counter')
      const incrementEl = document.querySelector('.increment')
      const decrementEl = document.querySelector('.decrement')

      let counter = 0
      counterEl.innerHTML = counter

      incrementEl.addEventListener('click', () => {
        counter += 1
        counterEl.innerHTML = counter
      })
      decrementEl.addEventListener('click', () => {
        counter -= 1
        counterEl.innerHTML = counter
      })
    </script>
  </body>
</html>
